Jackie Robinson broke the baseball color line when he started at first base for the Brooklyn Dodgers on April 15, in 1947. When the Dodgers signed Robinson, they heralded the end of racial segregation in professional baseball that had relegated black players to the Negro leagues since the 1880s. Robinson was inducted into the Baseball Hall of Fame in 1962.
In 1997, MLB retired his uniform number 42 across all major league teams; he was the first professional athlete in any sport to be so honored. MLB also adopted a new annual tradition, “Jackie Robinson Day”, for the first time on April 15, 2004, on which every player on every team wears No. 42. Read more (Wikipedia)